Integrated package containing MEMS acoustic sensor and environmental sensor and methodology for fabricating same

ABSTRACT

An integrated package of at least one environmental sensor and at least one MEMS acoustic sensor is disclosed. The package contains a shared port that exposes both sensors to the environment, wherein the environmental sensor measures characteristics of the environment and the acoustic sensor measures sound waves. The port exposes the environmental sensor to an air flow and the acoustic sensor to sound waves. An example of the acoustic sensor is a microphone and an example of the environmental sensor is a humidity sensor.

TECHNICAL FIELD

Embodiments of the subject disclosure relate generally to acoustic andenvironmental sensors, and particularly to the integrated packaging ofthese sensors.

BACKGROUND

Integration of component devices of a consumer electronics product isdesirable to reduce form factor. Integration often results in sizereduction because multiple devices become parts of one integratedsystem. The integrated system itself can then be progressively reducedin size over time. Integration of multiple devices into one system iscomplex and made more complex in cases where each device is of adifferent type and has different manufacturing requirements.

For example, acoustic sensors (e.g. microphones) are utilized inapplications with environmental sensors (e.g. humidity and/ortemperature sensors). Presently, the humidity and/or temperaturesensors, while being a part of the same product as the microphone, arepackaged separately from the microphone. Stated differently, the typesof sensors are located as discrete components within the same product.This leads to increased real estate cost in addition to complexity ofmanufacturing, as each component must be assembled separately on to thehost circuit board of the product. A single package comprising aplurality of sensors would significantly simplify manufacturing, reducecosts, and reduce overall board area. Furthermore if the sensors can beintegrated along with an application specific integrated circuit (ASIC)in the same package, further cost and size reductions can be realized.

However, efforts to integrate the foregoing sensors are hindered byseveral challenges. One such challenge is in bonding the microphone, apart of the acoustic sensor, to an application specific integratedcircuit (ASIC). Temperatures used for such bonding are typically andapproximately 430 degrees Celsius and higher. Environmental sensingmaterials, such as polymers, are not likely to survive at suchtemperatures. Another challenge occurs during release etching, a processutilized during manufacturing of the acoustic sensor, when the polymerexperiences adverse effects rendering it defective in most if not allcases. Such shortcomings have prevented the integration of acousticsensors with environmental sensors on the same IC substrate and/orpackage substrate.

It would be desirable to have an integrated package and methodology formaking an integrated package that contains both acoustic andenvironmental sensors and also an ASIC for processing data generated bythese sensors.

SUMMARY

An embodiment of the subject disclosure includes a packaged device thatincludes at least one environmental sensor, at least one acousticsensor, and at least one port connecting the device to the environment,wherein the at least one environmental sensor measures characteristicsof the environment and the at least one acoustic sensor measures soundwaves. The port exposes the environmental sensor and the acoustic sensorto the environment. An example of an acoustic sensor is a microphone andan example of an environmental sensor is a humidity sensor.

A further understanding of the nature and the advantages of particularembodiments disclosed herein may be realized by reference of theremaining portions of the specification and the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an exemplary integrated package in which the acousticsensor and the environmental sensor are aligned with the port.

FIG. 2 illustrates an exemplary integrated package in which theenvironmental sensor is located in the back cavity of the acousticsensor.

FIG. 3 illustrates an exemplary integrated package in which the acousticsensor and the environmental sensor are located on top of and attachedto an ASIC.

FIG. 4 illustrates an exemplary integrated package in which the acousticsensor and the environmental sensor are attached to different ASICs.

FIG. 5 illustrates an exemplary integrated package in which themicrophone is wire bonded to an ASIC.

FIG. 6 illustrates an exemplary integrated package in which the port islocated in the cover (or lid) of the package.

FIG. 7 illustrates an exemplary integrated package in which themicrophone is attached to the cover and is aligned with the port that islocated in the cover of the package.

FIG. 8 illustrates an exemplary environmental sensor.

FIG. 9 illustrates another exemplary environmental sensor.

FIG. 10 illustrates an exemplary application of an integrated packageincluding an acoustic sensor and an environmental sensor.

DETAILED DESCRIPTION

In the described embodiments, integrated circuit (IC) substrate mayrefer to a silicon substrate with electrical circuits, typically CMOScircuits. Also, a CMOS IC substrate may include an ASIC. A cavity mayrefer to a recess in a substrate or a lid (cover). An enclosure mayrefer to a fully enclosed volume typically surrounding the MEMSstructure and typically formed by the IC substrate, structural layer,MEMS substrate, and the standoff seal ring. A port may be an openingthrough a substrate to expose the MEMS structure to the surroundingenvironment. It is to be appreciated that an enclosure would include anacoustic port, in various embodiments of the subject disclosure.

In the described embodiments, a chip includes at least one substratetypically formed from a semiconductor material. A single chip may beformed from multiple substrates, where the substrates are mechanicallybonded to preserve the functionality. Multiple chips include at leasttwo substrates, wherein the two substrates are electrically connected,but do not require mechanical bonding. A package provides electricalconnection between the bond pads on the chip to a metal pad that can besoldered to a printed circuit board (PCB). A package typically comprisesa substrate and a cover. It is to be appreciated that the packagehermitically seals its components, with the exception that the portopening of the package allows for air flow in and out of the package.Also, it is to be appreciated that the package provides an acousticseal, with the exception that the port opening of the package allows forsound waves to enter and exit the package.

In the described embodiments, a cavity may refer to an opening orrecession in a substrate wafer and enclosure may refer to a fullyenclosed space that includes a port opening. In the describedembodiments, back cavity may refer to a partial enclosed cavityequalized to ambient pressure via Pressure Equalization Channels (PEC).In various aspects of the subject disclosure, the back cavity providesacoustic sealing, with the exception that it allows sound waves to enterand exit by way of an acoustic MEMS sensor element (e.g. a diaphragm).In some embodiments, back cavity is also referred to as back chamber. Aback cavity formed with in the CMOS-MEMS device can be referred to asintegrated back cavity.

In the described embodiments, a rigid structure within an acousticsystem that moves when subject to force may be referred to as a plate. Aback plate may be a perforated plate used as an electrode toelectrically sense the movable plate. In the described embodiments,perforations refer to acoustic openings for reducing air damping inmoving plates. Acoustic port may be an opening for sensing the acousticpressure. Acoustic barrier may be a structure that prevents acousticpressure from reaching certain portions of the device. Linkage is astructure that provides compliant attachment to a substrate by way of ananchor.

Referring now to FIG. 1, a device 100 is shown, in accordance with anembodiment of the subject disclosure. The device 100 is shown to includean acoustic sensor 102, an environmental sensor 104, a port 106, a lid(or cover) 108, a package substrate 130, an integrated circuit (IC)substrate 112 and a back cavity 134. The acoustic sensor 102 is shownphysically connected to the environmental sensor 104. Solder 114connects device 100 to external substrates. The lid 108 and the packagesubstrate 130 form a “package”.

In the embodiment of FIG. 1, the port 106 is shown aligned with anacoustic sensor port 128, as will be shown and discussed herein, theseports need not be aligned. In addition, port 106 in package substrate130 can receive acoustic waves for sensing by acoustic sensor 102, and,depending on the embodiment can receive other environmental phenomena.The acoustic sensor 102 includes a back cavity 134, sensor element 120(e.g. a diaphragm), acoustic sensor substrate 126, acoustic sensor port128, and IC substrate 112.

The acoustic sensor 102 is shown positioned above the IC substrate 112,in accordance with one of many other embodiments of the subjectdisclosure too numerous to list. Wire bond 116 electrically couples theIC substrate 112 to the package substrate 130. Through the physicalconnection between the IC substrate 112 and the acoustic sensor 102, theacoustic sensor 102 is also electrically coupled to the packagesubstrate 130. The environmental sensor 104 is shown positioned belowthe package substrate 130 and IC substrate 112, which again is merelyone embodiment of many others.

The environmental sensor 104 is shown to include sense electrodes 144,and an environmental sensing material 105 built directly on packagesubstrate 130. The environmental sensor 104 is also shown to include aheater 122 and in some embodiments can also serve as a temperaturesensor. The port 106 is shown formed in the package substrate 130 andthe IC substrate 112. The port 106 is shown to extend through theenvironmental sensing material 105. In some embodiments, theenvironmental sensor 104 can be built to one side of the porteliminating the extension of the port 106 through the environmentalsensing material 105.

In some embodiments, the acoustic sensor 102 is a microphone, such as,but not limited to, a MEMS microphone. In such embodiments, the sensorelement 120 is a micromachined structure that moves in response to anacoustic signal. Each standoff 118 is a conductive path and separatesthe sensor element 120 from the IC substrate 112. The sensor element 120and a conductive layer that is typically the top aluminum layer disposedon the IC substrate 112 collectively form a capacitor. The capacitancevaries as the distance between the sensor element 120 and the ICsubstrate 112 varies due to the movement of the sensor element 120caused by acoustic pressure vibrations. These vibrations are caused bysound waves entering the device 100 through the port 106.

The operation of the environmental sensor 104 may use capacitancevariation, resistance variation, or mass loading to sense the particularenvironmental characteristic being sensed. Such characteristics, withoutlimitation, are temperature, humidity, pressure, biological, and manymore too numerous to list.

To this end, the IC substrate 112 plays a dual role in that it processeschanges in two sensor elements, for example, sensor elements associatedwith acoustic sensor 102 and environmental sensor 104. The sensorelement of the acoustic sensor 102 and the sensor element of theenvironmental sensor 104 may share the electronic processingcapabilities of the IC substrate 112.

It is understood that dimensional terms, such as “top”, “bottom”,“side”, and the like, as used herein, are relative and their use indescribing various embodiments is merely for the sake of discussion andproviding examples. It is understood that other dimensional relationsmay be employed and/or the same dimensional relation may be an oppositerelation as that which is disclosed herein. For example, the acousticsensor 102 may be flipped such that it is formed on top of the packagesubstrate 130 and under the IC substrate 112. In fact, practically, andin accordance with alternative embodiments, the environmental sensor 104may be formed on top of the acoustic sensor 102.

In an embodiment of the subject disclosure, the lid 108 is made ofmetal. In an embodiment of the subject disclosure, the package substrate130 is made of a polymer, or ceramic. In an embodiment of the subjectdisclosure, the acoustic sensor 102 is a microphone or any otheracoustic sensor with a port (or exposure). In yet another embodiment ofthe subject disclosure, the environmental sensor 104 is a gas,temperature, pressure, biological, nanoparticles, spores, pathogen, orchemical sensor, or any other suitable sensor that is suitable forexposure to environment by way of the port 106.

In some embodiments, the acoustic sensor 102 is a microphone, such asbut not limited to, a MEMS microphone. In some embodiments, theintegrated back cavity 134 is a part of the microphone, as well known tothose in the field.

In some embodiments of the subject disclosure, the acoustic sensor 102and the environmental sensor 104 are formed on a single substrate, suchas the package substrate 130. In some embodiments of the subjectdisclosure, the acoustic sensor 102 and the environmental sensor 104 areformed on separate (or different) substrates. In some embodiments of thesubject disclosure, the acoustic sensor 102 and the environmental sensor104 are formed on a single IC substrate. In some embodiments of thesubject disclosure, the acoustic sensor 102 and the environmental sensor104 are formed on different package substrates.

While one acoustic sensor and one environmental sensor is shown anddiscussed herein, it is understood that more than one of each suchsensors may be employed. The foregoing alternatives apply to theremaining embodiments of the subject disclosure as shown and discussedherein in addition to others not necessarily shown or discussed hereinbut contemplated.

It is understood that alternatives and variations of FIG. 1 apply to theremaining embodiments in addition to other contemplated embodimentsunless expressly indicated otherwise.

FIG. 2 shows a device 200, in accordance with another embodiment of thesubject disclosure. The device 200 is analogous to the device 100 exceptfor the following. The environment sensor 204 is disposed laterally withrespect to IC substrate 212 and acoustic sensor 102, and is disposedwithin the acoustic sensor back cavity 234. Acoustic sensor 102 is shownpositioned and coupled to the IC substrate 212 and IC substrate 212 isshown positioned on the package substrate 230. In fact, in theembodiment of FIG. 2, the environmental sensor 204 is shown to not bepositioned on top of the port 106. The environmental sensor 204 is shownto include capacitor 244, environmental sensing material 205, and aheater 222, for which, in some embodiments can also serve as atemperature sensor. In addition, as with device 100 of FIG. 1, device200 can comprise a wire bond 116 that electrically couples the ICsubstrate 212 to the package substrate 230 and solder 114 that connectsdevice 200 to external substrates. The lid 108 and the package substrate230 can form a “package”.

FIG. 3 shows a device 300, in accordance with another embodiment of thesubject disclosure. In the embodiment of FIG. 3, the environmentalsensor 304 is shown to include capacitor 344, environmental sensingmaterial 305, and heater 322. The environmental sensor 304 is shownformed on top of the IC substrate 112, which as in the embodiment ofFIG. 1, is shown disposed on the package substrate 130. No wire bondingof the environmental sensor 304 to the IC substrate 112 is necessary inthe embodiment of FIG. 3 because the environmental sensor 304 isdisposed and formed on top of the IC substrate 112. Accordingly, theenvironmental sensor 304 is physically and electrically coupled to theIC substrate 112 and formed on the package substrate 130. The acousticsensor 102 is physically and electrically coupled to the IC 112. Asopposed to remaining embodiments, the environmental sensor 304 and theacoustic sensor 102 of FIG. 3 are fully integrated onto one single ICsubstrate 112. As with device 100 of FIG. 1, device 300 is shown toinclude an acoustic sensor 102, an environmental sensor 304, a port 106,a lid (or cover) 108, a package substrate 130, an integrated circuit(IC) substrate 112, and a back cavity 334. In addition, device 300 cancomprise solder 114 that connects device 300 to external substrates. Thelid 108 and the package substrate 130 form a “package”.

FIG. 4 shows a device 400, in accordance with another embodiment of thesubject disclosure. In the embodiment of FIG. 4, the environmentalsensor 404 is shown to include the environmental sensing material 405,the capacitor 444, and the heater 422. The environmental sensor 404 isshown to be stand-alone and not a part of the IC substrate 112 in thatit is formed on an environmental sensor substrate 450 that is disposedon top of the package substrate 130. The environmental sensor substrate450 can comprise an IC substrate. Thus, the environmental sensor 404 isphysically and electrically coupled to the environmental sensorsubstrate 450 comprising the IC substrate. In such case, the ICsubstrate 450 can also provide functionality for some part of, or allof, signal processing of environmental sensor's 404 data. Wire bond 452electrically couples the environmental sensor 404 to the packagesubstrate 130. IC substrate 112 is independently electrically coupled tothe package substrate 130 through the wire bond 116. The acoustic sensor102 is shown formed on top of the IC substrate 112, as in the embodimentof FIG. 1. As with device 100 of FIG. 1, device 400 is shown to includean acoustic sensor 102, an environmental sensor 404, a port 106, a lid(or cover) 108, a package substrate 130, an integrated circuit (IC)substrate 112, and a back cavity. In addition, device 400 can comprisesolder that connects device 400 to external substrates. The lid 108 andthe package substrate 130 form a “package”.

FIG. 5 shows a device 500, in accordance with another embodiment of thesubject disclosure. The device 500 is analogous to the device 400 exceptthat in FIG. 4 the acoustic sensor is connected to and formed on top ofthe IC substrate 112, whereas the acoustic sensor 502 is not formed ontop of the IC substrate. That is, environmental sensor substrate 550comprising an IC substrate can include functionality configured toprocess both data generated by the environmental sensor 504 as well asdata generated by the acoustic sensor 502. The environmental sensor 504is shown to include the capacitor 544, the heater 522 and theenvironmental sensing material 505. The environmental sensor 504 isshown disposed and formed on top of the environmental sensor substrate550 comprising an IC substrate. Thus, the environmental sensor 504 isphysically and electrically coupled to the environmental sensorsubstrate 550 comprising an IC substrate. The environmental sensorsubstrate 550 comprising an IC substrate is shown formed on top of thepackage substrate 530 and is electrically coupled to it through the wirebond 552. The acoustic sensor 502 is shown disposed on top of thepackage substrate 530 and is electrically coupled to the environmentalsensor substrate 550 comprising an IC substrate through the wire bond554. As with device 400 of FIG. 4, device 500 is shown to include anacoustic sensor 502, an environmental sensor 504, a port 106, a lid (orcover) 108, a package substrate 530, and a back cavity. In addition,device 500 can comprise solder that connects device 500 to externalsubstrates. The lid 108 and the package substrate 530 form a “package”.

FIG. 6 shows a device 600, in accordance with yet another embodiment ofthe subject disclosure. The device 600 is analogous to the device 500except that the package substrate 630 has no port at the place where theenvironmental sensor 504 and the acoustic sensor 502 are positioned.Rather, it has a port 606 in the lid 608, at a place that issubstantially on top of the environmental sensor 504 and horizontallydisplaced from and positioned on top of the acoustic sensor 502. As withdevice 500 of FIG. 5, device 600 is shown to include an acoustic sensor502, an environmental sensor 504, a port 606, a lid (or cover) 608, apackage substrate 630, and a back cavity. The environmental sensor 504is shown to include the capacitor 544, the heater 522, and theenvironmental sensing material 505. The environmental sensor substrate550 comprising an IC substrate is shown formed on top of the packagesubstrate 630 and is electrically coupled to it through the wire bond552. The acoustic sensor 502 is shown disposed on top of the packagesubstrate 630 and is electrically coupled to the environmental sensorsubstrate 550 comprising an IC substrate through the wire bond 554. Inaddition, device 600 can comprise solder 114 that connects device 600 toexternal substrates. The lid 608 and the package substrate 630 form a“package”.

FIG. 7 shows a device 700, in accordance with another embodiment of thesubject disclosure. The embodiment of FIG. 7 is analogous to that ofFIG. 6 except that the acoustic sensor 702 is shown at a positionopposite to that of the environmental sensor 504. More specifically, theacoustic sensor 702 is shown to be disposed on the inner side of a lid708 comprising a substrate for acoustic sensor 702, and theenvironmental sensor 504 is shown disposed on the package substrate 730,similar to the position of the environmental sensor 504 of the device600. A port 706 is shown through the top portion of the lid 708 andextending through the acoustic sensor 702. The acoustic sensor 702 iselectrically coupled through wire bond 754 to lid 708 instead. FIG. 7depicts an entire package comprising substantially the same materialslike that of printed circuit boards, where three packaging layers, e.g.,package substrate 730, wall enclosure layer 710, and lid 708 comprisinga substrate for acoustic sensor 702, are used. Accordingly, packagesubstrate 730 supports wall enclosure layer 710, which defines thepackage enclosure height, and lid 708 is then assembled onto the wallenclosure layer to complete the enclosure that represents the backvolume of the acoustic sensor 702. As with device 600 of FIG. 6, theenvironmental sensor substrate 550 comprising an IC substrate is shownformed on top of the package substrate 730 and is electrically coupledto it through the wire bond 552. In addition, device 700 can comprisesolder 114 that connects device 700 to external substrates. The lid 708and the package substrate 730 form a “package”.

FIG. 8 shows a part of the environmental sensor 800, in accordance withan embodiment of the subject disclosure. The environmental sensor 800 isshown to have a laminate substrate 802, metal lines 801 (e.g., metallines 801 a, 801 b, and 801 c), sense capacitor 144 comprising metalelectrodes 801 a and 801 b, and environmental sensing material 805. Thesense capacitor 144 provides a variable capacitance between metalelectrodes 801 a and 801 b in response to a change in a particularenvironmental characteristic associated with and experienced byenvironmental sensing material 805. The laminate substrate 802 can bethe substrate 130 or substrate 230 of FIGS. 1 and 2, respectively, uponwhich the environmental sensors 104 or 204 may be formed. In theembodiment of FIG. 8, a metal or semiconducting layer 803, comprising alayer of material that has a relatively higher resistance than metallayer 801 and formed on laminate substrate 802, can form a heatingelement and/or resistance-based temperature sensor by being connectedbetween metal lines 801 b and 801 c formed on layer 803.

FIG. 9 shows a part of the environmental sensor 900, in accordance withan embodiment of the subject disclosure. The sensor 900 is analogous tothe sensor 800 except that environmental sensor 900 has two metallayers, metal layer 901 and metal layer 910, which are separated bymaterial of laminate substrate 902, and thus, are not in direct physicalcontact. Sense capacitance can be measured across interdigitatedelectrodes 901 a and 901 b formed in single layer metal 901.Environmental sensing material 905 is shown formed on top of metal layer901 and between the interdigitated electrodes 901 a and 901 b formed bymetal layer 901. Metal layer 910 can be used as a heater element as wellas temperature sensor.

It is also possible to transform the heating element into a temperaturesensor if the metal resistance versus temperature behavior iswell-characterized. In a typical laminate process, all exposed parts ofthe metal layer will be plated with gold finishing. The potentialcorrosion due to humid environmental sensing material no longer exists.

Accordingly, with the right choice of humidity-sensitive material, it ispossible to fully integrate humidity sensor right on top of the ICsubstrate where it could sustain high temperature during semiconductorprocessing (<450° C.) and some release processing (such as vapor HFrelease etch.). Thus, such a fully-integrated embodiment, an example ofwhich is shown in FIG. 3, is attractive, considering the smallest formfactor and lowest manufacturing cost achievable.

FIG. 10 shows an exemplary application of the various embodiments of thesubject disclosure. More specifically, a host system 1000 is shown toinclude a port 1006, an environmental sensor 1004 and an acoustic sensor1002, collectively defining a hybrid device 1009. The hybrid device 1009has its own port that may or may not be aligned with the port 1006.

Examples of the acoustic sensor 1002 are the acoustic sensors of FIGS.1-7; similarly, examples of the environmental sensor 1004 are theenvironmental sensors of FIGS. 1-7. The host system 1000 may be anysystem requiring acoustic and environmental sensors, such as asmartphone, a smart watch or a wearable exercise device. Otherapplications of the hybrid device 1009 are contemplated and too numerousto list here.

Although the description has been provided with respect to particularembodiments thereof, these particular embodiments are merelyillustrative and not restrictive.

As used herein, the term “top”, “bottom”, “left”, and “right” arerelative and merely examples of the structures disclosed. It isunderstood that the relation of the structures may be opposite to thatwhich is stated. For example, the term “bottom”, as used herein, may be“top” in other embodiments of the subject disclosure.

As used in the description herein and throughout the claims that follow,“a”, “an”, and “the” includes plural references unless the contextclearly dictates otherwise. Also, as used in the description herein andthroughout the claims that follow, the meaning of “in” includes “in” and“on” unless the context clearly dictates otherwise.

Thus, while particular embodiments have been described herein, latitudesof modification, various changes, and substitutions are intended in theforegoing disclosures, and it will be appreciated that in some instancessome features of particular embodiments will be employed without acorresponding use of other features without departing from the scope andspirit as set forth. Therefore, many modifications may be made to adapta particular situation or material to the essential scope and spirit.

What is claimed is:
 1. A device comprising: a package; a MEMS acousticsensing element comprising a diaphragm disposed in the package; anintegrated circuit (IC) disposed in the package and comprising an ICsubstrate having an environmental sensing material of an environmentalsensor disposed in the IC substrate, wherein the environmental sensorcomprises the environmental sensing material in a configurationsensitive to a change in an environmental characteristic independent ofpressure experienced by the environmental sensor, wherein theenvironmental sensor is comprised of a plurality of segments of theenvironmental sensing material interspersed between and in directcontact with a plurality of metal electrodes, wherein the plurality ofmetal electrodes are subjected to a variable electrical environment inresponse to the change in the environmental characteristic, and whereinat least one of the plurality of metal electrodes comprises a heatingelement of the environmental sensor, and wherein the IC is configured toprocess data generated by the MEMS acoustic sensing element and theenvironmental sensor; and a port disposed in the package configured toreceive acoustic waves for the MEMS acoustic sensing element and air forthe environmental sensor; wherein, the package includes an acousticallysealed back cavity that encompasses the MEMS acoustic sensing elementand the IC comprising the environmental sensor.
 2. The device of claim1, wherein the MEMS acoustic sensing element includes a MEMS microphone.3. The device of claim 1, wherein the environmental sensor includes oneof a humidity, gas, temperature, chemical, biological parameter,nanoparticles, spore, or pathogen sensor.
 4. The device of claim 1,wherein the port includes one of a square, rectangular or circularshaped cavity.
 5. The device of claim 1, wherein the environmentalsensor is disposed in a manner that is aligned with the port.
 6. Amethod for making a package comprising: forming a package substrate;forming a MEMS acoustic sensor element on the package substrate; formingan application specific integrated circuit (ASIC) chip above the packagesubstrate comprising forming an ASIC substrate having an environmentalsensing material of an environmental sensor disposed in the ASICsubstrate, wherein the environmental sensor comprises the environmentalsensing material in a configuration sensitive to a change in anenvironmental characteristic independent of pressure experienced by theenvironmental sensor, wherein the forming the ASIC chip includesdepositing a plurality of segments of the environmental sensing materialinterspersed between a plurality of metal electrodes in direct contactwith the environmental sensing material, thereby fabricating anenvironmental sensor arrangement that provides a variable electricalcharacteristic in response to the change in the environmentalcharacteristic, and includes configuring at least one of the pluralityof metal electrodes as a heating element of the environmental sensor;forming electrical connections between the ASIC chip and the MEMSacoustic sensor element and between the ASIC chip and the environmentalsensor; forming a cover attached to the package substrate, wherein thecover defines a back cavity that encompasses the MEMS acoustic sensorelement and the ASIC chip comprising the environmental sensor; andforming an opening in the package, wherein the opening is configured toreceive sound waves and air flow.
 7. The method of claim 6, whereinforming the package substrate includes forming a laminate substrate. 8.The method of claim 6, wherein forming the environmental sensor includesaligning the environmental sensor with the opening.
 9. An integratedcircuit chip comprising: a substrate; a port disposed in the substrate;an environmental sensor aligned with the port; an application specificintegrated circuit (ASIC) disposed above the substrate and comprising anenvironmental sensing material of the environmental sensor, wherein theenvironmental sensor comprises the environmental sensing material in aconfiguration sensitive to a change in an environmental characteristicunrelated to pressure experienced by the environmental sensor, whereinthe environmental sensor is comprised of a plurality of segments of theenvironmental sensing material interspersed between and in directcontact with a plurality of metal electrodes, wherein the plurality ofmetal electrodes are subjected to a variable electrical environment inresponse to the change in the environmental characteristic, and whereinat least one of the plurality of metal electrodes comprises a heatingelement of the environmental sensor; a MEMS acoustic sensor elementdisposed above the ASIC, wherein the ASIC is configured to process datagenerated by the MEMS acoustic sensor element and the environmentalsensor; and a cover attached to the substrate, wherein the cover definesa back cavity that encompasses the MEMS acoustic sensor element and theASIC comprising the environmental sensor.
 10. An integrated circuit chipcomprising: a substrate; a port disposed in the substrate; anapplication specific integrated circuit (ASIC) mechanically affixeddirectly to the substrate and comprising an environmental sensingmaterial of an environmental sensor, wherein the environmental sensorcomprises the environmental sensing material in a configurationinsensitive to a change in pressure experienced by the environmentalsensor, wherein the environmental sensor is comprised of a plurality ofsegments of the environmental sensing material interspersed between andin direct contact with a plurality of metal electrodes, wherein theplurality of metal electrodes are subjected to a variable electricalenvironment in response to the change in the environmentalcharacteristic, and wherein at least one of the plurality of metalelectrodes comprises a heating element of the environmental sensor; aMEMS acoustic sensor element disposed above the port and mechanicallyaffixed directly to the substrate apart from and adjacent to the ASIC;and a cover attached to the substrate, wherein the cover defines a backcavity that encompasses the MEMS acoustic sensor element and the ASICcomprising the environmental sensor.